JPH06155725A - Transfer type ink jet recording device - Google Patents

Abstract

PURPOSE:To improve the ink transfer performance for a recording device forming an ink image in an intermediate medium and transferring the same to a recording medium. CONSTITUTION:A device consists of an ink jet recording head jet spraying ink drops correspondingly to a data to be recorded, an ink image retaining drum 1 receiving ink drops and a press roller 3 disposed movably back and forth in a transfer zone of the ink image retaining drum 1 and generating slip while applying nip pressure between the roller and the ink image retaining drum 1. When the ink image formed on the ink image retaining drum 1 reaches the transfer zone, a recording paper P is brought into contact with the drum 1 by the press roller 3. At that time, as the ink image retaining drum 1 is deformed elastically and the slip of the recording aper P is generated to the ink image retaining drum 1 by the press roller 3, shearing force is applied in the various directions between the ink image and the ink image retaining drum 1 to peel off the ink image easily and transfer the same to the recording paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer technique in a recording apparatus of a type in which an ink droplet is ejected from a nozzle to a cylindrical ink image holding means based on print data and a pattern formed on the cylindrical ink image holding means is transferred to a recording sheet. Regarding

[0002]

2. Description of the Related Art Ink jet recording in which an ink jet type line recording head for ejecting ink droplets from a nozzle is driven based on print data, and the ink droplets generated at this time are received by a recording paper to record a pattern matching the print data. The device has been put to practical use. Such a device that directly ejects ink droplets onto the recording paper has a simple structure, but on the other hand, the recording paper that receives the ink droplets has the opposite properties such that there is little ink bleeding and it is well compatible with the ink. It is necessary to prepare a sheet having both of these characteristics, and there is an inconvenience that the recording paper is restricted when trying to obtain high print quality.

In order to solve such a problem, an ink image holding drum is formed of a material such as an ink drop generated on the basis of print data in which ink bleeding such as silicone rubber is small and the attached ink is easily peeled off. There is proposed an ink jet recording apparatus of a system in which an ink pattern is formed on a drum by receiving the ink with a recording medium, the ink pattern is semi-dried and then transferred to a recording sheet (US Pat.
5,099,256). When the ink pattern is printed in a semi-dried state on the recording paper in this manner, it is possible to print on the recording medium without causing ink bleeding.

[0004]

On the other hand, on the other hand, since the ink is in a semi-dried state at the time of transfer,
The adhesiveness of the ink to the recording paper is reduced, and particularly in a pattern formed by continuous dots such as a line segment, a part of the ink image is likely to be untransferred, which may deteriorate the print quality. is there. In the printer of the type in which the image once formed on the image holding drum is transferred to the recording sheet as described above, it has been proposed to provide a speed difference between the image holding drum and the recording sheet in order to improve transfer efficiency. (Japanese Patent Laid-Open No. 4-70785), the technique disclosed here transfers an image held by electrostatic force to a recording sheet by electrostatic force. It cannot be used as is for printing methods that are not used. The present invention has been made in view of the above problems, and an object of the present invention is to provide a novel transfer capable of reliably transferring the ink of the ink image holding drum to a recording sheet regardless of the dry state of the ink. Type inkjet recording apparatus.

[0005]

In order to solve such a problem, according to the present invention, an ink jet recording head for ejecting ink droplets corresponding to recorded data, and an elastic deformable structure for receiving the ink droplets. An ink image holding means and a pressing roller arranged so as to be able to move forward and backward in a transfer area of the ink image holding means and having a rotation speed set so as to cause a slip in a state where a nip pressure is applied to the ink image holding means are provided. .

[0006]

When the ink pattern formed on the ink image holding means reaches the transfer area, the recording paper is pressed against the ink image by the pressing roller. Since the pressure roller slides while applying pressure to the ink image holding means, the recording paper gives a shearing force between the ink image holding means and the ink image, and the ink image is transferred onto the surface of the ink image holding means. Will be easily torn off.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. FIG. 1 shows an embodiment of the present invention. In the figure, reference numeral 1 is an ink image holding drum, a shaft 21 of which is connected to a pulse motor 2 through a transmission mechanism 20 such as a timing belt, and a constant rotation. A layer 25 of a material that does not cause ink bleeding and has good wettability with respect to ink is formed on the surface of the drum body 24 that is rotationally driven in the direction indicated by arrow A at a speed. There is.

In the figure, reference numeral 2 is an ink jet type recording head, and in this embodiment, a plurality of characters, for example, a lateral width area of a maximum size recording sheet can be printed by one scanning.
The 2000 nozzle openings are arranged in a straight line or arranged in a zigzag pattern with each digit shifted vertically.
A plurality of nozzles, for example, 400 nozzles are arranged at a pitch of a plurality of dots in the main scanning direction, for example, at an interval of 5 dots, and the recording head is equivalent to one dot of the ink image holding drum for each rotation of the ink image holding drum of the ink image holding drum. It is also possible to use a recording head which moves a plurality of times, for example, five times to form an image for one page of the ink image holding drum. Each of these nozzle openings communicates with a pressure chamber to which ink is supplied from an ink tank, similarly to a normal serial printer, and an energy generating source such as a piezoelectric element or a heating element provided in these pressure chambers. Is operated according to the print data to cause the ink in the pressure chambers to fly from the nozzle openings.

Reference numeral 3 in the drawing is a pressing roller, and a material having a friction coefficient with respect to the recording paper P larger than that of the recording paper P with respect to the ink image holding drum 1, for example, a friction layer 3a such as rubber or ceramic sprayed on the surface. Along with
A shaft 30 is pivotally supported on the base 31. Then, it is connected to a pulse motor 33 fixed to the same base 31 via a transmission mechanism 32, and a slight speed difference ΔV is applied to the pressing roller 3 so as to cause a slip with the surface peripheral speed V1 of the ink image holding drum 1. It can be driven at its own speed V2. In addition, the base 31 is attached to the pressing mechanism 34,
It is configured to be able to reciprocate in the direction of reference numeral C in the drawing.

In the figure, reference numeral 35 is a control device which detects the rotational position of the ink image holding drum 1 and outputs print data to the recording head 2 when the home position reaches the recording head 2 and ink. When the image formation is complete,
The recording sheet is conveyed here at the time when the home position of the holding drum 1 reaches the transfer area, and at the same time, the pressing mechanism 34 is operated to press the pressing roller 3 against the surface of the ink image holding drum 1 with a constant nip pressure. , A predetermined peripheral speed difference Δ between the ink image holding drum 1 and the pressing roller 3.
The pulse motor 33 is controlled so that V is generated. Reference numeral 38 in the drawing denotes a paper feed roller that supplies the recording paper to the transfer area.

Next, the operation of the thus constructed apparatus will be described with reference to FIG. When the pressure roller 3 is separated from the ink image holding drum 1 (FIG. 2I), the ink image holding drum 1 is rotated at a constant speed V1, and when the home position faces the inkjet recording head 2, printing from the host or the like is performed. Inkjet recording head for data 2
Output to. The ink droplets ejected from the inkjet recording head 2 sequentially form an ink image that matches the print data on the surface of the ink image holding drum 1.

When an ink image is formed while the ink image holding drum 1 is rotated in this way, the solvent forming the ink in the ink image is semi-dried due to evaporation of the solvent.
When a predetermined amount, for example, one page of ink image is formed on the ink image holding drum 1, the recording paper P is moved by the paper feed roller 38 at the timing when the home position of the ink image holding drum 1 moves to the transfer area. Supply to the transfer area. When the leading end of the recording paper P reaches the printing area, the pressing mechanism 34 moves the pressing roller 3 in the direction of the arrow D to press it against the ink image holding drum 1 with a predetermined nip pressure (II in FIG. 2).

As a result, the recording paper P is sandwiched between the ink image holding drum 1 and the pressing roller 3 and is pressed against the ink pattern image with a constant force F by the pressing force from the pressing roller 3 (FIG. 2 III). . Thereafter, while maintaining this state, the ink image on the ink image holding drum 1 is transferred to the recording paper P.

In this process, since the pressing roller 3 has a larger friction coefficient with respect to the recording paper P than the ink image holding drum 1, the recording paper P moves at a speed V2 which is as close as possible to the peripheral speed V2 of the pressing roller 3. To do. As a result, the recording paper P has a speed difference ΔV = | V1-V2 | with respect to the peripheral speed V1 of the ink image holding drum 1, and the ink image 3
7 will slide on the ink holding drum 1.
At the same time, since the surface of the ink image holding drum 1 is made of an elastic material such as silicon rubber, as shown in FIG. 3, the contact area between the ink image holding drum 1 and the pressing roller 3,
That is, a recess is formed in the area where the recording paper P is in contact. As a result, the ink holding drum 1 forms a convex area K and a concave area J in a narrow transfer area, thereby rubbing the ink image on the surface and causing minute cracks in the ink image. The transfer efficiency onto the recording paper will be further improved.

When the transfer efficiency due to such a rubbing phenomenon was investigated, it was found that there was a very large correlation between the nip pressure and the slip ratio as shown in FIG. That is, in order to obtain a practically satisfactory constant transfer efficiency, the slip ratio may be small when the nip pressure is large, and the slip ratio must be large when the nip pressure is small.
Indicates the lower limit of these conditions, and when both the slip ratio and the nip pressure are larger than those of the curve M, it is possible to obtain sufficient transfer characteristics. By the way, if the slip ratio and the nip pressure are larger than the curve M, it is possible to obtain a sufficient transfer characteristic, but if the slip ratio exceeds 5%, the distortion of the image transferred to the recording paper becomes large, and the printing is performed. There is a problem that quality is deteriorated. On the other hand, with regard to the nip pressure, when it is attempted to design a printing device with a practical size, the mechanism for applying a pressure of about 50 kilograms to a recording paper having a width of 35 cm is the limit.
The upper limit is about 0 gf / cm.

Since there is a practical limit to the occurrence of slippage while applying a large nip pressure, when these conditions are combined together, after all, the conditions of the recording paper are within the range shown by hatching in FIG. It has been found that the ink can be transferred onto the recording paper with high efficiency by selecting the nip pressure and the slip ratio in relation to the paper quality and the ink holding power of the ink image holding means. Especially when the ordinary office paper is used as the recording paper, the nip pressure is fixed at a value of about 150 to 600 gf / cm, while the slip ratio takes into consideration the paper quality of the recording paper and the ink holding power of the ink image holding means. Therefore, it is desirable to select an appropriate value, that is, to be able to adjust the rotational speed of the holding drum 1 and the pressing roller 3 from the outside.

When the transfer for one page is completed in this way, the pressing by the pressing mechanism 34 is released and the pressing roller 3 is separated from the ink image holding drum 1 (FIG. 2).
I).

FIG. 5 shows an embodiment of a data processing device for dealing with the case where a large rate of slip must be given in order to improve such transfer characteristics. Reference numeral 40 in the figure is a slip ratio setting means, which obtains a speed reference signal from an ink image holding drum driving means (not shown),
A speed difference ΔV for giving an arbitrary slip ratio between the ink image holding drum 1 and the rotation speed of the pressure roller 3 is set, and the data set here is a pulse motor connected to the pressure roller 3. It is output to the motor drive means 41 of 33 to control the speed of the motor 33. Reference numeral 42 denotes an enlarging / reducing means for receiving a print signal from the host, which corresponds to the data from the slip ratio setting means 40 and which is used as an image buffer 43.
The size of the bitmap data to be expanded in the sub-scanning direction, that is, the size of the ink image holding drum 1 in the circumferential direction is expanded or contracted. Such one-way enlargement / reduction of image data can be easily realized by software.

According to this embodiment, even if a high slip ratio is set by the slip ratio setting means 40 in order to obtain a sufficient transfer performance, the bitmap data generated by the print data corresponding to this slip ratio is enlarged. Since the distortion is corrected by the reducing means 42, the image after transfer is not distorted.

FIG. 6 shows another embodiment of the data processing apparatus. In the figure, reference numeral 46 is a position detecting means, and ink is generated based on a signal from an encoder 47 for detecting the position of the ink image holding drum 1. A signal corresponding to the position of the image holding drum 1 is output. Reference numeral 45 denotes a print position calculating means, which is an optimum sub-scanning direction, that is, paper feeding, in order to form an image in which the pattern transferred onto the recording paper is not distorted regardless of the slip ratio from the slip ratio setting means 40. The dot formation position in the direction is calculated, and the print timing signal is output from the print pulse generator 48 based on the calculation result. According to this embodiment, since only the data to be printed is the calculation target, it can be realized with a relatively small scale circuit configuration.

FIG. 7 shows another embodiment of the pressing roller. In FIG. 7, reference numeral 51 is a braking means for applying a load to the pressing roller 50, which presses the base 31 driven by the pressing mechanism 34. It is attached integrally with the roller 3.

In this embodiment, when the recording paper P is conveyed to the transfer area and the pressing mechanism 34 is operated at the same time when the formation of the ink image on the ink image holding drum 1 is completed,
The pressure roller 50 is pressed against the ink image holding drum 1 so as to sandwich the recording paper P. The pressure roller 50 receives the rotational force from the ink image holding drum 1 via the recording paper P and tries to rotate in synchronization with the ink image holding drum 1. However, this is subject to a load by the braking means 51. Moreover, since the frictional force with respect to the recording paper P is larger than that of the ink image holding drum 1, slippage occurs between the recording paper P and the ink image holding drum 1 and a speed difference ΔV is generated. As a result, similarly to the above, the ink image on the ink image holding drum 1 is subjected to shearing force between the ink image and the surface of the ink holding drum 1, and is reliably transferred onto the recording paper P. Of course, the speed difference ΔV between the pressing roller 50 and the ink image holding drum 1 depends on the magnitude of the load acting on the pressing roller 50. Therefore, by adjusting the magnitude of the load by the braking means 51, the transfer characteristics can be improved. Can be adjusted.

FIG. 8 shows another embodiment of the present invention in which the ink image holding means is constituted by a belt.
Reference numeral 0 denotes an ink image holding means constituted by an endless belt, which is constituted by an elastic material such as the above-mentioned silicon rubber and has two rollers 61, 62 in a region facing the recording head 2.
In the area facing the pressing roller 3, it is supported by a driving roller 63 having a relatively large diameter, which is connected to a pulse motor 65 via a transmission mechanism 64.

According to this embodiment, when the drive roller 3 is rotated at a constant speed in the direction of the reference numeral in the figure, the ink image holding means 60 passes the front surface of the recording head 2 at a constant speed. When print data is output to the recording head 2 in this state, a pattern is formed on the surface of the ink image holding means 60 by the ink droplets ejected from the recording head 2. In this way, when the predetermined amount of data is recorded on the ink image holding means 60, the pressing roller 3 is moved to the ink image holding means 60 side according to the home position, and the recording paper is conveyed. As a result, the recording paper P moves while being pressed against the surface of the ink image holding means 60 by the pressing roller 3. As a result, the ink image is transferred onto the recording paper by the same operation as in the first embodiment. According to this embodiment, it is possible to increase the distance between the recording area and the transfer area,
Not only can the time from ink pattern formation to transfer be extended and the ink image can be dried sufficiently,
If necessary, it is possible to dispose a cooling unit for removing the ink image remaining in the ink image holding unit, a heater for blowing off the solvent of the ink having a low drying rate, and a blowing unit.

In this embodiment, the case where the line recording head is used has been described as an example, but it is clear that the same effect can be obtained even if the serial recording head is used.

[0026]

As described above, in the present invention,
An ink jet recording head that ejects ink droplets corresponding to recorded data, an ink image holding unit that receives the ink droplets and that is elastically deformable, and an ink image holding unit that is arranged so as to be capable of advancing and retracting in a transfer area of the ink image holding unit. Since a pressure roller whose rotation speed is set so as to cause slippage in a state where a nip pressure is applied is applied to the ink image which has become a semi-dried state on the surface of the ink image holding means, a peeling force is applied. Thus, the ink image can be reliably transferred to the recording medium, the print quality can be improved and the cleaning interval of the ink image holding means can be extended.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an apparatus showing an embodiment of the present invention.

FIGS. 2 (I) to (III) are explanatory views showing the operation of the above-mentioned apparatus, respectively.

FIG. 3 is an explanatory diagram showing a phenomenon in a transfer area in the same apparatus.

FIG. 4 is a diagram showing a relationship between a nip pressure, a slip ratio, and a transfer efficiency.

FIG. 5 is a block diagram showing an embodiment of a control device suitable for controlling the above device.

FIG. 6 is a block diagram showing an embodiment of a control device suitable for controlling the above device.

FIG. 7 is a configuration diagram showing another embodiment of the pressing roller.

FIG. 8 is a configuration diagram showing an embodiment in which a belt is used as an ink image holding unit.

[Explanation of symbols]

 1 Ink Image Holding Drum 2 Inkjet Recording Head 3 Pressing Roller 23 Pulse Motor 24 Drum Body 25 Ink Image Holding Layer 31 Base 33 Pulse Motor 34 Pressing Mechanism P Recording Medium

Claims (6)

[Claims] 1. An ink jet recording head for ejecting ink droplets corresponding to recorded data, an ink image holding means capable of receiving the ink droplets and elastically deformable, and capable of advancing and retreating to a transfer area of the ink image holding means. A transfer type ink jet recording apparatus provided with a pressing roller which is arranged and whose rotation speed is set so as to cause a slip in a state where a nip pressure is applied to an ink image holding means. 2. The transfer type ink jet recording apparatus according to claim 1, wherein the ink image holding means is a drum. 3. The transfer type ink jet recording apparatus according to claim 1, wherein the ink image holding means is composed of an endless belt. 4. The transfer type ink jet type ink jet recording apparatus according to claim 1, wherein the slip ratio between the ink image holding means and the recording paper is 0.2 to 5%, and the nip pressure of the pressing roller is in the range of 150 to 1500 gf / cm. Recording device. 5. An ink jet recording head for ejecting ink droplets corresponding to recorded data, an ink image holding means for receiving the ink droplets, and an ink image arranged so as to be able to move forward and backward in a transfer area of the ink image holding means. A pressing roller whose rotation speed is set so as to cause slippage in a state where a nip pressure is applied to the holding means, and an enlarging / reducing means for enlarging or reducing the input recording data according to the slip ratio and outputting it to the recording head. A transfer type ink jet recording device provided. 6. An ink jet recording head which ejects ink droplets corresponding to recording data, an ink image holding means for receiving the ink droplets, and an ink image which is arranged in a transfer area of the ink image holding means so as to be able to move forward and backward. A transfer-type ink jet recording apparatus comprising a pressing roller whose rotation speed is set so as to cause a slip in a state where a nip pressure is applied to a holding means, and a means for determining an ink ejection timing according to the slip ratio.